Hi, I am looking for a dump of Ublox GPS messages at or around a leap second event. Was a while since the last... In particular the message UBX-NAV-TIMELS (b5 62 01 26) which contains leap upcoming leap second info, and the seconds to/since the event. To know which second is considered as the '0' for the indicator in the message. Just NMEA messages around a leap second event would be intresting too. This is for my FPGA GPS/NTP project. Cheers, Håkan

Hi Håkan, > https://www.maths.tcd.ie/~dwmalone/time/leap2016/#nmea has a NMEA recording from an MAX-M8q from 2016. As for UBX-NAV-TIMELS: Are you talking about the field 'timeToLsEvent'? As the NMEA shows u-blox counting to second 60 I would assume it working like this: 11:59:58 timeToLsEvent=+2 11:59:59 timeToLsEvent=+1 11:59:60 timeToLsEvent=0 00:00:00 timeToLsEvent=-1 00:00:01 timeToLsEvent=-2 Or for negative leap seconds: 11:59:58 timeToLsEvent=+1 00:00:00 timeToLsEvent=-1 But these are only educated guesses. Regards, Markus Am 26.07.2023 um 19:21 schrieb Håkan T Johansson via time-nuts: > > Hi, > > I am looking for a dump of Ublox GPS messages at or around a leap second > event.  Was a while since the last... > > In particular the message UBX-NAV-TIMELS (b5 62 01 26) which contains > leap upcoming leap second info, and the seconds to/since the event.  To > know which second is considered as the '0' for the indicator in the > message. > > Just NMEA messages around a leap second event would be intresting too. > > This is for my FPGA GPS/NTP project. > > Cheers, > Håkan > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com

Hi Markus, thanks! Yes, it is the field 'timeToLsEvent' I am mostly curious about. Looking at the output from an LEA-M8T now, it gives reports that should extrapolate to having been: 2021-11-28 00:00:00 timeToLsEvent=0 2021-11-28 00:00:01 timeToLsEvent=-1 after the non-event at/after 2021-11-27 23:59:59, i.e. 256 weeks after the most recent actual leap-second 2016-12-31. Since GPS only report leap second placement with 8 bits for the week number, this is as much as the ublox receiver can know. That however does not tell how it would have looked after a real event. This is the current report from the LEA-M8T (other messages omitted): PPS-1 UART-1: UBX-NAV-TIMELS: 1b4093e8 00 00 00 00 02 12 02 00 fcdf5f11=-607d6h59m59s 0889 0007 00 00 00 03 UART-1: $GNRMC,065959.00,A,5742.76987,N,01201.36421,E,0.034,,280723,,,A*60 PPS-1 UART-1: UBX-NAV-TIMELS: 1b4097d0 00 00 00 00 02 12 02 00 fcdf5f10=-607d7h0m0s 0889 0007 00 00 00 03 UART-1: $GNRMC,070000.00,A,5742.76987,N,01201.36420,E,0.034,,280723,,,A*60 PPS-1 UART-1: UBX-NAV-TIMELS: 1b409bb8 00 00 00 00 02 12 02 00 fcdf5f0f=-607d7h0m1s 0889 0007 00 00 00 03 UART-1: $GNRMC,070001.00,A,5742.76987,N,01201.36418,E,0.034,,280723,,,A*6A 607 days is since then, i.e. 607 + 256*7 = 2399 days since 2016-12-31. (365+365+365+366+365+365 + 31+28+31+30+31+30 + 27 = 2399) For leap-second adjustment handling, I would anyhow base its happening on the actual time, and not the timeToLsEvent count-down hitting a specific value. So easiest is likely to accept timeToLsEvent if it is counting and within +/- a few seconds around 0 at the critical time, and the leap delta to be non-zero. As well as the time being 23:59:5x and the day the last of the month, or only 06-30 or 12-31 for now. Most interesting would be the testing infrastructure I need to make probable that the code is working. It does not make sense to handle a rare circumstance and then get other problems with normal behaviour. My default handling right now is that after 7 reports of mismatching time (or just missing) $G?RMC (which would be 7 s after a leap-second) it stops claiming to be syncronised when reporting according to the old scale. Then it takes another 8 reports until it accepts and reports according to the new timescale. Cheers, Håkan On Thu, 27 Jul 2023, Markus Kleinhenz via time-nuts wrote: > Hi Håkan, > >> https://www.maths.tcd.ie/~dwmalone/time/leap2016/#nmea > > has a NMEA recording from an MAX-M8q from 2016. > > As for UBX-NAV-TIMELS: > > Are you talking about the field 'timeToLsEvent'? > > As the NMEA shows u-blox counting to second 60 I would assume it working > like this: > > 11:59:58 timeToLsEvent=+2 > 11:59:59 timeToLsEvent=+1 > 11:59:60 timeToLsEvent=0 > 00:00:00 timeToLsEvent=-1 > 00:00:01 timeToLsEvent=-2 > > Or for negative leap seconds: > > 11:59:58 timeToLsEvent=+1 > 00:00:00 timeToLsEvent=-1 > > But these are only educated guesses. > > > Regards, > Markus > > > Am 26.07.2023 um 19:21 schrieb Håkan T Johansson via time-nuts: >> >> Hi, >> >> I am looking for a dump of Ublox GPS messages at or around a leap second >> event.  Was a while since the last... >> >> In particular the message UBX-NAV-TIMELS (b5 62 01 26) which contains >> leap upcoming leap second info, and the seconds to/since the event.  To >> know which second is considered as the '0' for the indicator in the >> message. >> >> Just NMEA messages around a leap second event would be intresting too. >> >> This is for my FPGA GPS/NTP project. >> >> Cheers, >> Håkan >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe send an email to time-nuts-leave@lists.febo.com > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe send an email to time-nuts-leave@lists.febo.com >

You could raise a question on u-blox support? The company ought to know the answer, or at least someone in the user community. https://portal.u-blox.com/s/ John.